engine wouldn't start ...now overheating

Back in post 7 you state that the engine was rebuilt a year ago. Post 40 states new manifolds & risers in 2011. Do you know if a certified mechanic did this work? Im not throwing darts at anyones work. Im just really interested in this thread & asking the question in an effort to learn or even help shed some light.

A rebuild, manifolds & risers seems like a fair amount of work on the engine in less than 4 years. How many hours on the boat since the rebuild? Since the manifolds? Im just wondering if this may have been an ongoing problem. If it now needs a head gasket - Well, Im out of my league here. Time for me to back off.

"What happens if it is a gasket", you ask. Well, someone is going to spend some more money.
 
Well I had a mechanic come take a look... Started the engine and took a look at the circulating pump and could here the bearings and see water dripping ... So he thinks it's definitely a circulating pump.... So YOU GUYS WERE RIGHT ! ... He was going to change it but I told him im going order the pump and change it myself ...hopefully that fixes the problem.... I'll check back after I change it this weekend ...

he did thinks 4 years was a little early on the manifolds as well...


thanks so much guys you all are a godsend (so is this forum in general) ..

I went from knowing jack about boats(and mechanics in general) .. To changing the oil, fuel filter , impeller, anchor , batteries , t stat , .and still learning .. But never thought I'd be able to do this stuff myself

Hopefully changing this circulator pump will be the last thing this season
 
Do your shopping! I just did mine and most folks had mine listed around $700! I found a brand new one for $390! Then I found the parts I needed to rebuild the old one and now I have that one as a spare. Do not rebluild and use it as the pump, it won't last long.
 
Do your shopping! I just did mine and most folks had mine listed around $700! I found a brand new one for $390! Then I found the parts I needed to rebuild the old one and now I have that one as a spare. Do not rebluild and use it as the pump, it won't last long.

WOW, i am surprised at that price for a circulation pump....when i replaced the one on the 5.7L in the 215EC it cost around $110 if i remember correctly....i would think the 350 MAG and the 5.7 may even share the same circulation pump since they are both GM 350 cid marine engines.....

are you sure you are not talking about the price for a new sea water pump instead of a circulation pump?....

cliff
 
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he did thinks 4 years was a little early on the manifolds as well...

from your profile info it looks like you are boating in a fresh water lake....if that is true you should not be concerned about corrosion issues with the exhaust components....you should get at least 10+ years out of exhaust components when used with fresh water and probably many more years than that...my first boat was a 1986 Chris Craft...it was always used in fresh water and it had the original exhaust components...they were still in excellent shape when i gave the boat to my brother-in-law....

cliff
 
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are you sure you are not talking about the price for a new sea water pump instead of a circulation pump?....

Cliff your right, it was my sea water pump and impeller. A bearing and pump shaft seal failed.
 
I went from knowing jack about boats(and mechanics in general) .. To changing the oil, fuel filter , impeller, anchor , batteries , t stat , .and still learning .. But never thought I'd be able to do this stuff myself

that is how most (if not all) of us old 'gear heads' gained the little bit of mechanical knowledge we have....by not being afraid to learn new things and rolling up the sleeves and digging in....i started working on my 'stuff' as a teenager because i could not afford to pay anyone else to work on it.....even if you are fortunate enough and can afford to pay someone to work on your car/boat there is a certain amount of satisfaction and pride gained from successfully diagnosing a problem and taking the proper corrective actions or just performing routine service/maintenance....not only do you save money but you can also be sure the job was done the right way and since you have a good working knowledge of your boat you can better handle emergencies as they pop up....

cliff
 
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just like cliff said............mine all started with a little lawn mower engine mini-bike...and hasn't stopped since.
 
Other than a dripping weep hole / bearing, I've never heard of a failing circulator pump. You have that and it needs to be replaced, no question. However my hunch is that this problem will persist.

When you pull the pump, make sure to inspect all water passages, including hoses. Look for any blockages, sludge, sand, etc. Open the pump, expect to see signs of failure....something lie the metal fan is either broken, or spinning on the shaft.

You said you *did* replace the T-Stat, right? You may have a bad (new) T-Stat. I'd verify that it is working by dropping it in water, and heating it. Scan the water, and verify the temp when / if it opens. Just don't use the good pots. If I did that in my house, the Mrs would have me or the pots replaced - haha
 
from your profile info it looks like you are boating in a fresh water lake....if that is true you should not be concerned about corrosion issues with the exhaust components....you should get at least 10+ years out of exhaust components when used with fresh water and probably many more years than that...my first boat was a 1986 Chris Craft...it was always used in fresh water and it had the original exhaust components...they were still in excellent shape when i gave the boat to my brother-in-law....

cliff

Actually im in saltwater .. How long do manifolds last in saltwater ..? Also the mechanic told me I should be flushing the engine with freshwater EVERY time I take her out.... Haven't been doing that ... Do you just close the sea cock , drain the engine ,mand put a water hose in the flush socket ... And run the engine for a couple minutes ?
Do you guys do this every time.. ?
 
Other than a dripping weep hole / bearing, I've never heard of a failing circulator pump. You have that and it needs to be replaced, no question. However my hunch is that this problem will persist.

When you pull the pump, make sure to inspect all water passages, including hoses. Look for any blockages, sludge, sand, etc. Open the pump, expect to see signs of failure....something lie the metal fan is either broken, or spinning on the shaft.

You said you *did* replace the T-Stat, right? You may have a bad (new) T-Stat. I'd verify that it is working by dropping it in water, and heating it. Scan the water, and verify the temp when / if it opens. Just don't use the good pots. If I did that in my house, the Mrs would have me or the pots replaced - haha


Well ill looks like you were right.., I changed the pump... Overheating persists... Sigh .. I'm not sure where to go from here ... Pretty bummed..
 
When did all this start? After the engine rebuild?
 
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You posted this earlier.

I also went went out today and took some temp reading with laser temp gun
I started the engine at the same time and compared at idle


the starboard engine temp stopped increasing at 154 (port was at that time 152) :
tstat both engines =154
manifolds both engines =170
i let let the port engine get up to 167 and took another set of reading (starboard still 154 )
tstat port =170 star=154
manifolds =port =200/195 starboard 190/185
risers both engines =70-74

so so it seems the port manifolds were a little hotter but not significantly so.(could be a manifold or a cooling issue ?)




Your manifolds are very hot, mine run around 90*-110* on a FWC system running on muffs or in the water.

I would pull the risers off and inspect them, if they look good pull the manifolds & plugs. If all is good you will at least eliminated that as a problem & have new gaskets.

You may need to do a compression & leak down test to eliminate a blown head gasket or crack somewhere, I would do this now before going any farther.

Best of luck

Edit: I wouldn't rule out a circulation pump except both engines are running hot, but I wouldn't start throwing money at it yet till you've eliminated all you can.

Both sides port & starboard engine manifolds are running way to hot, if they were changed at the same time in 2011 I'd say you need to inspect them & go from there.
 
One more thing if it were me I wouldn't run these engines till you've found the problem, you could hydroloc the engine, at the least you're over heating the oil causing it to break down which can cause things like sludge to develop, poor lubrication on the cam, lifters, bearings etc.

All it will take is one turn of the key & it will cost you a new engine.

I've done it on a $20,000 (in 1970 dollars) 426 hemi when a carb leaked while hauling the car to Phoenix for a race, we pulled in late & needed to get the car thru tech inspection, all it took was for the engine to fire up for about 1 second putting a rod thru the pan. The only part of that engine that was usable was the manifold & carbs. Luckily we had another engine in the trailer.
 
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Well ill looks like you were right.., I changed the pump... Overheating persists... Sigh .. I'm not sure where to go from here ... Pretty bummed..
Looking over your temp numbers, water is flowing through the risers. The engine is acting as if The thermostat is not opening. If it is, the water has no flow it will overheat as it does at idle. The coolant around the cylinders is not moving.. Take a pic, so we can see exactly what the routing of the cooling system looks like. You'll need to pull some hoses and verify water flow at various points
 
Remove the thermostat and see what temps you get. Also, you had said the motor had been rebuilt. Has this issue been going on since the rebuild?
 
Well ill looks like you were right.., I changed the pump... Overheating persists... Sigh .. I'm not sure where to go from here ... Pretty bummed..

sorry to hear that but that pump needed to be replaced anyway if it had water weeping out and had a loud bearing....that was just a problem waiting to happen in the near future....

i still think a compression test is needed to rule out a blown head gasket.....

cliff
 
ok guys so I had the mechanic come take a second look he ran a compression test... everything was good... after a couple hours of searching found that the water distribution housing was bad.. apparently the valve was stuck... will replace in the next couple of days on both engines... ...cautiously optimistic.. hopefully fixing this will fix the issue.. .if it does kinda annoyed that such a simple problem .. wish I would have thought about it as its such an easy fix before I changed the water pump t stat ... etc.... but I guess better than a head gasket blow out! plus I learned a lot and gained a lot of confidence in repairing issues...
 

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